Supplementary figures from: Is 3D, a more accurate quantitative method than 2D, crucial for analyzing disparity patterns in extinct marine arthropods (Trilobita)?
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Aug 21, 2025 version files 957.79 KB
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README.md
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SupplementaryFigures.pdf
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Abstract
Phacopid trilobites are well documented during the Paleozoic. Nevertheless, while 2D quantitative analyses have advanced our understanding of the morphological relationships among trilobites, the quantification of their morphological traits in 3D remains rarely documented. Based on two sets of morphological data (head and tail), 2D versus 3D shape quantification approaches were used to explore shape allometries as well as to explore how the shape variations can be explained by the phylogenetic relationships among phacopid trilobite species for the first time. We demonstrate that (1) there are similar patterns of morphological variability across taxa in 3D and 2D; (2) there are rather congruent results between 3D and 2D to discriminate taxa; (3) 2D and 3D landmarks capture different levels of detail, and the third dimension in 3D is very important for making taxonomic distinctions at the genus level; (4) there is congruity between 2D and 3D datasets for allometric patterns with results showing similar allometric slopes among species exhibiting a glabellar length decrease during growth leading to wider cephala; (5) the phylomorphospaces show tree branches that do not intersect, suggesting possible phylogenetic constraints on morphospace occupation for each species and supporting the idea that the Austerops and Morocops groups are sister clades that experienced different modes of morphological evolution; and (6) the morphological descriptors in morphometric analyses in 2D and 3D throughout phacopid evolution are effective.
Dataset DOI: 10.5061/dryad.rn8pk0pmj
Description of the data and file structure
The pdf file is structured to provide six supplementary figures from: Is 3D, a more accurate quantitative method than 2D, crucial for analyzing disparity patterns in extinct marine arthropods (Trilobita)?
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File: SupplementaryFigures.pdf
Description:
*Supplementary Figure A. 3D plot of shape change vector after a generalized Procrustes analysis (GPA) on 60 specimen configurations (cephala) associated with PC1 min and max, PC2 min and max and PC3 min and max, respectively in 1) frontal view; 2) dorsal view; and 3) lateral view. Exaggerated displacement factor along axes 0.1.
*Supplementary Figure B. 3D plot of shape change vector after a generalized Procrustes analysis (GPA) on 41 specimen configurations (pygidia) associated with PC1 min and max, PC2 min and max and PC3 min and max, respectively in 1) dorsal view; 2) frontal view; and 3) lateral view. Scale 0.1.
*Supplementary Figure C. Min and max mesh warping (3D) in dorsal view depicting allometric shape variations between the six studied species having at least 3 individuals for 60 cephala. Scale 0.1.
*Supplementary Figure F. Scatter plots of 3D partial Procrustes distances against 2D partial Procrustes distances for 1) cephala, and 2) pygidia; as well as scatter plots of centroid sizes from 2D and 3D configurations for 3) cephala, and 4) pygidia.
*Supplementary Figure D. 3D mesh warping and 2D thin plate spline deformation grids in dorsal view after a generalized Procrustes analysis (GPA) performed for five species having at least 3 individuals for 41 pygidia. Scale 0.1.
*Supplementary Figure E. Scatter plot of fitted PC1 scores (shape scores predicted by multivariate regression of shape on size) against predictor as the log-transformed centroid sizes showing allometric trajectories among five studied species for 60 cephala in 3D and 2D. 95% CIs account for nearly 75% of fitted value variation.
*Supplementary Figure F. Scatter plots of 3D partial Procrustes distances against 2D partial Procrustes distances for 1) cephala, and 2) pygidia; as well as scatter plots of centroid sizes from 2D and 3D configurations for 3) cephala, and 4) pygidia.
The pdf file is structured to provide six supplementary figures from: Is 3D, a more accurate quantitative method than 2D, crucial for analyzing disparity patterns in extinct marine arthropods (Trilobita)?